<!DOCTYPE html>
<html lang="en">
 
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>许愿墙</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
 
        html {
            height: 100%;
            background: linear-gradient(0deg, rgb(171, 212, 238), deepskyblue);
        }
 
        body {
            position: relative;
        }
 
        .container {
            width: 100%;
            height: 630px;
            position: relative;
        }
 
        input[id="res"] {
            width: 300px;
            height: 40px;
            position: fixed;
            bottom: 30px;
            left: 50%;
            margin-left: -150px;
            padding-left: 15px;
            border: 1px solid #ccc;
            outline: none;
            border-radius: 5px;
        }
 
        .item {
            width: 150px;
            height: 150px;
            position: absolute;
            top: 100px;
            left: 100px;
            box-shadow: 0 2px 10px 1px rgba(0, 0, 0, 0.2);
            padding: 10px;
            border-radius: 15px/5px 10px 10px 0;
            transform: skew(-1deg);
            cursor: move;
        }
 
        .item span {
            position: absolute;
            right: 6px;
            bottom: 4px;
            font-size: 12px;
            color: #eee;
            cursor: pointer;
        }
 
        .comfirmBtn {
            width: 100px;
            height: 40px;
            position: fixed;
            bottom: 31px;
            left: 64%;
            border: none;
            outline: none;
            border:1px solid;
            border-radius: 10px;
            cursor: pointer;
        }
    </style>
</head>
 
<body>
    <div class="container"></div>
    <input type="text" name="res" id="res" placeholder="随便说说吧...点击确认按钮发布">
    <button class="comfirmBtn">点击发布</button>
    <script>
        // 获取DOM元素
        let container = document.getElementsByClassName('container')[0];
        let btn = document.getElementsByClassName('comfirmBtn')[0];
        // 默认的许愿单文字
        let wishes = ['新年来好运', '能找一份好工作', '日语等级考试通过', '能交上女朋友', '新年来好运', '能找一份好工作', '日语等级考试通过', '能交上女朋友'];
        // 许愿单随机背景颜色
        let bgcColors = ['#96c2f1', '#bbe1f1', '#e3e197', '#f8b3d0', '#ffcc00', 'rgba(255,123,123,1)', 'yellowgreen', 'pink', 'skyblue'];
        // 渲染函数 新增一个div元素 做好css配置以后将该div返回
        let render = function (wish) {
            // 生成随机数据
            let bgcColorIndex = Math.floor(Math.random() * bgcColors.length);
            let randomTop = Math.floor(Math.random() * (630 - 150)); // container容器的高减去150
            let randomLeft = Math.floor(Math.random() * (window.innerWidth - 175)); // left值在减去盒子宽度150的基础上多减去了25px
            let content = `<div class="item" style="top:${randomTop}px;left:${randomLeft}px;background-color:${bgcColors[bgcColorIndex]}">${wish}<span>关闭</span></div>`;
            container.innerHTML += content;
        }
        // 页面刚开始加载时 将默认的许愿单加载到页面上
        window.onload = function () {
            // 遍历所有默认的许愿单 将其渲染到页面上面
            for (let i = 0; i < wishes.length; i++) {
                render(wishes[i]);
            }
        }
        // 发布新内容函数
        let newContent = function () {
            if (res.value !== '') {
                let inputText = res.value;
                render(inputText);
                res.value = '';
            } else {
                alert('不能为空！');
            }
        }
        // 有两种方式可以添加新的愿望 按回车键 或者 点击发布按钮
        document.onkeyup = function (e) {
            if (e.keyCode === 13) {
                newContent();
            }
        }
        // 为确认按钮添加点击事件
        btn.onclick = newContent;
 
        // 通过事件委托 给整个document绑定点击事件 但是只有点击span元素的时候 移除其父节点
        document.onclick = function (e) {
            if (e.target.nodeName === 'SPAN') {
                container.removeChild(e.target.parentNode);
            }
        }
 
        // 设置许愿单拖动
        container.onmousedown = function (e) {
            if (e.target.className === 'item') {
                let offsetX = parseInt(e.target.style.left); // 获取当前的x轴距离
                let offsetY = parseInt(e.target.style.top); // 获取当前的y轴距离
                let innerX = event.clientX - offsetX; // 获取鼠标在方块内的x轴距
                let innerY = event.clientY - offsetY; // 获取鼠标在方块内的y轴距
                let that = e.target;
                document.onmousemove = function (e) {
                    that.style.left = event.clientX - innerX + "px";
                    that.style.top = event.clientY - innerY + "px";
                    // 边界判断
                    if (parseInt(that.style.left) <= 0) // 左边边界
                    {
                        that.style.left = "0px";
                    }
                    if (parseInt(that.style.top) <= 0) // 上边边界
                    {
                        that.style.top = "0px";
                    }
                    if (parseInt(that.style.left) >= window.innerWidth - 175) // 右边边界 = 窗口宽度 - 盒子大小 稍微多减去了25px
                    {
                        that.style.left = window.innerWidth - 175 + "px";
                    }
                    if (parseInt(that.style.top) >= 480) // 下边边界 = 630 - 150
                    {
                        that.style.top = 480 + "px";
                    }
                }
 
                document.onmouseup = function () {
                    document.onmousemove = null;
                    document.onmouseup = null;
                }
 
 
            }
 
 
 
        }
    </script>
</body>
 
</html>